Matthew Haley, Head of the Book Department, tells Lucinda Bredin why his career is going according to the script

One never knows what you are going to find, read – or indeed hear – in the Book Department. Felix Pryor, the manuscript expert, is reading aloud in a sonorous voice, "...there is no doubt about the club whose spirit you represent. I mean the Reform Club, the official abiding Place of Upper Middle 'Liberalism', which shelters the most notorious bugger in London..."

It is a letter from the archive of A.G. Gardiner (1865-1946), who received it when he was editor of the Daily News. Sent by Lord Alfred Douglas, Oscar Wilde's lover and the cause of Wilde's downfall, it is part of a collection, to be auctioned on 19 March in Knightsbridge, that also includes a letter from Woodrow Wilson about his thoughts on the League of Nations, one from Charles Dodgson (aka Lewis Carroll) on how he wished he'd never written those books, and a letter from Churchill concerning his role in the Tonypandy riots. Documents of history, every single one.

Matthew Haley, who became head of the department on the retirement of the legendary David Park, is sifting through more treasures on the shelves. Bram Stoker's Dracula sits next to a set of law books that range from the 15th to the 19th century. The law books are part of a 20-pallet consignment – estimated at £1.2m – that came from The Los Angeles County Law Library. As Haley says, "We had to hire a forklift to take them off the lorry. Absolutely mammoth task, but a lot of fun. It's certainly the biggest quantity of books I have ever had to deal with. But I think we won the consignment because we've had a history of success with collections of law books, and at the Oxford salerooms we can sell books at all sorts of prices."

Haley was not always obsessed with books. The only child of an accountant (his mother died when he was young), he grew up in Bristol "reading computer magazines and comic books". But then an inspirational English teacher "suddenly revealed to us that beneath the text there was another meaning other than the literal meaning.

This just absolutely blew me away and from that moment on I was reading voraciously." Haley went to Oxford to read English, where another teacher affected the path of his life. "My professor at Lincoln College took us down to the rare book library. And I saw all these old books and thought, 'This is pretty cool.'"

After a year working at the Taylor Institution Library in Oxford, Haley applied for a position as a junior cataloguer at Bonhams in 2004. "David Park interviewed me and told me afterwards that I got the job because I had good shoes."

It was going to New York that Haley felt was the making of him. He arrived in 2008, initially covering maternity leave, but he stayed for five years. "One of the loose ends dangling was some documents supposedly signed by Molière, the French playwright. There was an assumption that they were not quite right, but I couldn't understand why. So I contacted the national archives in France, and managed to iron out the story. We put it in with a $40,000 - 60,000 estimate and the market clearly agreed with me that it was 'right'. It sold for $330,000."

Haley has also expanded the horizons of the book department by establishing the Space Sale for space-age memorabilia – a niche not covered by other auction houses. Highlights have included Armstrong's One Small Step for a Man signed quotation ($150,000), the Apollo 11 lunar surface star chart ($218,000) and Leonov's 1975 ASTP space suit ($242,000). Another bonus, according to Haley, was that "I met David Scott and Edgar Mitchell, who had been on the moon."

This diversification might cast doubt on whether older historical documents will continue to hold their appeal. But Haley is emphatic on that point. "I would say we are dealing with a lot more manuscripts these days and interest is soaring. For instance, in June we sold the papers of Sir John Coape Sherbrooke, the Lieutenant-Governor of Nova Scotia during the War of 1812, for £433,250. It was a huge archive dating from the first quarter of the 19th century relating to British Canada with about 30 manuscript maps, including town plans of Toronto, Halifax and Montreal. That really was an attic find that our Cornish office unearthed. The owners were related to Sir John, but they were not aristocracy. The papers had been sitting in black wooden trunks that Sherbrooke himself had used to transport the archive around Canada 200 years ago."

But still, will future generations be interested in books? It's a topic Haley has addressed recently in a talk at the Hay Literary Festival. As he says, "It's true, the younger generation do read from a screen, but there is an increased fascination with the book as an object. Now that all types of printed matter – books, manuscripts, documents – are losing their use as a conveyor of information, they are being seen as works of art. Our sales are soaring."